The present invention relates to medical fluid pumps, in particular, a sterile centrifugal pump for pumping pressurized irrigating fluid into a joint undergoing arthroscopic surgery.
Whenever fluids are being pumped into a patient, it is essential that the fluid move only through a sterile environment. Therefore, for a pump to be useful in this environment, it is necessary that the mechanics of the pump be kept isolated from the fluid pathway.
U.S. Pat. No. 3,864,055 (Kletschka et al.) discloses a medical fluid pump in which a rotator spins within a chamber causing fluid to be propelled through the outlet of the chamber. The rotator within the chamber is mounted on a drive shaft that is journalled in a bearing. The shaft journalled within the bearings requires a precision fit which adds to the cost of such a pump. O-ring seals are used to maintain the chamber leak proof. The O-ring seals will work so long as they have not worn to the point where leaking may be possible. U.S. Pat. No. 5,178,515 (Tsuchya et al.), on the other hand, discloses a medical pump that is driven through a diaphragm. A rocker is connected to a shaft mounted through a diaphragm. The shaft is driven so as to rock the rocker within the chamber causing a rotating flow of fluid through the chamber and out through its outlets. In accordance with German Offenlegungsschraft 2918325 (Sempio), a pump chamber fed by an inlet has a ring which is swung around within the chamber causing the fluid to be forced out through the outlet. The drive shaft for the ring appears to be suspended within a diaphragm for hermetically sealing the chamber from the drive mechanism.